I seem to possess a double dose of the Scottish "careful with money" gene: I rarely let the moths out of my wallet (helped by not having easy access to UK shows or model shops). And I am supposedly focusing on a pre-WW2 LNE scenario. But when I saw Dapol had done a Class 26 BR diesel, I couldn't resist a blue one. I saw every loco in the class (bar one) when I was an kid, and others on rmweb spoke highly of the model. Only problem was, they'd all sold out online... I finally found one at Gaugemaster and after a bit of in-and-out-of-stock uncertainty, and a delay while Swiss customs took their pound of flesh (seven quid duty, plus another thirteen for the privilege of having them take a week to process the package!), it turned up in my mailbox.

This is my first model from Dapol. I followed the instructions to lubricate the bogie gears with a drop of light oil and run in for 30 minutes in each direction. It ran well out of the box on a test circle of 'N' track using a PICtroller (http://www.malcolmsm...a25jdmRXWjBGMlk), slow and controllable, but one direction of travel wasn't quite as good and there was an distracting loud ticking sound. No improvement after another half hour, so a closer look was called for.

I looked around online for help on how to take the model apart but apart from comments that the chassis was a tight fit in the body, and wires were easily detached, I didn't find much. So I took photos as I went along, and the rest of this blog entry is written around them. OK, taking a Dapol model to bits is not exactly finescale, but we all have to start somewhere! I hope they'll be useful to anyone else with a similar problem.

The bogies pop off easily with slight downwards pressure.

I took the bogies apart to check for faulty gears. They are rather like Farish bogies, but with more forgiving plastic. Gentle pressure from a screwdriver blade here

lets the gear block detach from the wheelframe. To remove the wheelsets, gently spread the wheelframe and edge the wheelset pinpoints out away from the frame pivot. If you try the other way, it will jam.

I now had the bogies in bits, but there was no sign of damaged gears.

They rotated smoothly in the towers and I could spin the wheels with my fingers. The problem must be elsewhere.

The worms were visible in the chassis, and gently pushing them round while using magnification, I could see what it was - a crushed edge on one worm.

It didn't look beyond my resources to fix, and in any case returning a model I'd already paid customs duty on, when I knew it was out of stock, seemed a waste of time and money. So I pressed on.

As others have commented, the chassis block is a very tight fit in the body, and there is a thin, separate frame moulding with buffers and fuel tanks attached. I was worried about breaking off the delicate buffers. I found the easiest way was, first, to very gently pop the buffer ends of the frame moulding out of the body with very light pressure from a screwdriver thus:

Do this at both ends. Then, firmly gripping the fuel tanks and the body, free the frame moulding from the body.

There are four small lugs which locate into the chassis block, and the idea is not to snap these off! This is hard if you can't see them. Here's a view with the baseplate re-attached, which shows where the lugs are.

With the baseplate safely stored out of the way of heavy objects, the next problem is to remove the chassis block from the body. I found it helped to slide thin shims between body and chassis to reduce any tendency to jam. Old 3.5" diskette covers are a good source of shim stock - about 0.02mm / 8 thou, and easily cut with sharp scissors. They also have a nice rounded edge to avoid damaging the body moulding. (Does anyone know what the metal is? It's non-magnetic).

You need to get a firm hold of the motor block to remove it, which is hard without risking damage to the body. I found the easiest way was to slide a bar through a small gap in the motor frame. (I am using tweezers, which is probably bad for them.... a small drill or length of axle steel might have been a smarter choice). It's then much easier to apply pressure without the risk of slipping or crushing the body.

Using this, the chassis can be gently edged out of the body at one end. Do this carefully as there are wires connecting the cab lighting units to the chassis block and they are not designed for much movement.

Once the chassis block is out at one end, remove the plug connector for the lighting unit by gently pushing its edges with a screwdriver or tweezers.

Now ease the other end of the chassis block free of the body and similarly remove the lighting plug.

I now had these bits:

Although I don't aim to DCC the model, I took out the blanking plug to look at it. It was unexpectedly rough.

It does its job, I suppose. I put it back in.

Next thing is to take the motor out of the chassis. The latter is in two metal halves, held together by four small plastic straps. It's easiest to remove two straps from the top of the chassis and then ease the motor out, disturbing the wiring as little as possible.(I didn't want to needlessly unsolder connections). Keep a finger over one end of the strap as you ease the other end over the lug with a screwdriver tip, or else the strap will fly across the room. Guess how I know...

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Now the chassis block can be split and the motor eased out.

Finally I could see the faulty worm clearly.

The worms are linked to the motor by nylon universal joints. These pop apart with gentle pressure, freeing the worm/shaft/UJ ball. The worm can then be gently popped out of its frame.

I held it in a pin vice, itself held firmly in a bench vice, and used a small file to smooth away gently the crushed edge. The damaged area was really paper thin - no problem to smooth away - poor inspection at the factory I suppose, or a cutting tool on an automatic machine run slightly past its useful life.

Re-assembly is a reversal of the above process. Make sure the small plastic thrust washers flanking the worm are correctly located when you fit it back in its frame. The motor has two plastic spacer cheeks next the flywheels which are free to rotate while the chassis is split: when you re-assemble, the narrower slot goes to the bottom of the chassis. Check that the suppressor capacitor and current-limiting thermistors locate correctly into the fuel tank, and that the bare leads next the motor brush tags do not short out to each other. (It seems odd these are not surface mount components, or else with better protected leads). Make sure the insulated wires leading to these components are correctly located in the chassis recess, and that they cannot be seen through the side window of the body.

Once reassembled, my model ran smoothly in both directions, with much less noise than before. However I'm not convinced that the slow running is quite as good as it was, or perhaps the motor cogs slightly more than it did. Or maybe I'm imagining it. Either way, done is done, and I'm glad the noise has gone.

Anyway, my next step is to think about conversion to 2FS. The 2mm Scale Association supplies replacement wheelsets for Farish diesels with wiper pickups, but the Dapol model uses split axles in an insulating bush (approved 2mm style!), with current pickup via the axle pinpoints running in conducting bearings. The 2mmSA wheelsets are therefore not suitable.

The split axle is 1.52mm diameter and comes to bits with finger pressure.

The gear is thinner than a 2mmSA gear, and had 20 teeth.

Comparison with a 2mmSA Farish wheelset drop-in replacement shows the difference between coarse and finescale profiles.

Using the half-axle as a basis, it should be possible to re-profile it, re-form the pinpoint (it will need shortened), and place it back in the insulating muff with a spacer washer at each side.

I suppose the choice is, enquire whether the 2mm SA's turning service can do this, or attempt to manufacture eight identical half-axle-and-wheel units from steel rod. I have an accurate lathe, but I don't have much skill in using it, and I wonder if I could hold the required tolerances. On one hand, this would be a good way to increase my skill level! ... and would leave the Dapol sets untouched if I ever wanted to sell the model or use it with coarse standards. On the other hand, getting the wheelsets reprofiled would get the job done accurately, cheaply and quickly.

Can anyone advise from experience?

The Dapol model's leading dimensions seem quite accurate:

The detailing looks pretty accurate for 26015 in the mid-1980s, but I am more interested in the mid-1970s. At this point, it had still had its train-heating water tank next the fuel tank, rather than the air compressor on the Dapol model (I believe the first seven locos in the class had these from early in their Scottish careers, for working MGR trains, but others only got them in the middle 1980s)

The original window style for earlier class members was drop lights rather than sliding windows. The model has the later style:

I am not sure if 26015 had round or oval buffers in the 1970s, though they were round by 1986. The model has round ones... not too difficult to fix, anyway. I'm also not sure about coil or bogie leaf springs. Does anyone know? Finally, in the 1970s 26015 had twin headlights and headcode discs as well as marker lights.

I don't seem to have a photo of 26015 in the 70s, but here's my own shot of 26013 coming off an Edinburgh arrival at Aberdeen on 22 August 1977, after taking over from a failed '40' at Dundee. The loco correctly displays a light engine disc code for the short trip to Ferryhill shed.

All of these things are little projects for me to add. No doubt the green version will have the correct variations, and maybe Dapol will in any case release a correct 1970s blue version in due course. I think they are to be congratulated on a superb model at an attractive price, and I'm looking forward to their promised Class 122 next year, examples of which also ran in the Dundee-Arbroath area when I was a kid. That LNE branch line may have to wait!

Graham

(edit to fix typos)